Re: [PATCH 5/5] power: supply: bq27xxx: Correct supply status with current draw

Hi!

quoted

quoted

The status reported directly by the battery controller is not always
reliable and should be corrected based on the current draw information.

This implements such a correction with a dedicated function, called
when retrieving the supply status.

quoted

quoted

@@ -1182,6 +1196,8 @@ static int bq27xxx_battery_status(struct

bq27xxx_device_info *di,
 		else
 			status = POWER_SUPPLY_STATUS_DISCHARGING;
 	} else {
+		curr = (int)((s16)curr) * 1000;

Umm.

As in "two casts in one expression -- too ugly to live".

quoted

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@@ -1190,6 +1206,18 @@ static int bq27xxx_battery_status(struct

bq27xxx_device_info *di,
 			status = POWER_SUPPLY_STATUS_CHARGING;
 	}
 
+
+	if (curr == 0 && status != POWER_SUPPLY_STATUS_NOT_CHARGING)
+		status = POWER_SUPPLY_STATUS_FULL;
+
+	if (status == POWER_SUPPLY_STATUS_FULL) {
+		/* Drawing or providing current when full */
+		if (curr > 0)
+			status = POWER_SUPPLY_STATUS_CHARGING;
+		else if (curr < 0)
+			status = POWER_SUPPLY_STATUS_DISCHARGING;
+	}

Are you sure this works? On N900, we normally see small currents to/from
"full" battery.

In my case, this works perfectly and I am quite surprised of what you're
describing. Is it the case when the battery has a PSU connected?

"PSU"? This is cellphone. It has USB connection and charges from that.

It has been charging for long while now, and current_now fluctuates
between 20706 and -2856. USB has limitted current, so I guess "draw
current from battery if we need more than USB can provide" is quite common.

pavel@n900:~$ cat /sys/class/power_supply/bq27200-0/current_now
5355
pavel@n900:~$ cat /sys/class/power_supply/bq27200-0/current_now
5355
pavel@n900:~$ cat /sys/class/power_supply/bq27200-0/current_now
-4105
pavel@n900:~$ cat /sys/class/power_supply/bq27200-0/current_now
-4105
pavel@n900:~$ cat /sys/class/power_supply/bq27200-0/current_now
-7675
pavel@n900:~$ cat /sys/class/power_supply/bq27200-0/current_now
-5712
pavel@n900:~$ #screen on
pavel@n900:~$ cat /sys/class/power_supply/bq27200-0/current_now
4641
pavel@n900:~$ cat /sys/class/power_supply/bq27200-0/current_now
4641
pavel@n900:~$ cat /sys/class/power_supply/bq27200-0/current_now
37842
pavel@n900:~$ cat /sys/class/power_supply/bq27200-0/current_now
16600
pavel@n900:~$

I guess I would consider this a hardware issue (leak currents) and we could
definitely set some range (in device-tree) to distinguish between full + leak
currents and bad reporting from the fuel gauge. That would work well in my case
too.

I'd pass to userspace what the controller reports. Yes, I seldom see
"STATUS_FULL" but that may be a problem we need to track down.



       	  	 	     		 	      	    	    	 Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html